Composite tubular member having consistent strength

Abstract

An axially extending tubular composite member having a plurality of plies and extending along a longitudinal axis has at least three plies with selectively structured fiber components in each ply. Typically an inner ply has at least one biaxial fiber component, an intermediate ply has at least an axial fiber component that typically is combined with two further fibers to form a triaxial fiber component. Another ply typically has a woven fiber component. A further ply having a biaxial component either replaces the ply of woven fiber or is disposed beneath it over the intermediate ply. A surface veil having fiber and an excess of resin material typically covers at least the innermost or outermost surface of the composite member. An internal web member can be provided, and typically also employs fibers and the matrix material.

Having described the invention, what is claimed as new and secured by letters patent is: 
     
       1. An axially extending tubular composite member having a plurality of plies and having primary bending stiffness along a longitudinal axis, said member having the improvement comprising A. at least one interior ply having at least a biaxial fiber component with a matrix material,   B. at least one intermediate ply having at least one axially extending fiber component disposed within said matrix material, said intermediate ply being exterior to said interior ply, and   C. at least one exterior ply having a woven fiber component with threads oriented parallel to said longitudinal axis and threads oriented transverse to said longitudinal axis, and disposed with said matrix material, said exterior ply being exterior to said intermediate ply.   
     
     
       2. A tubular composite member according to claim 1 having the further improvement comprising a veil covering said exterior ply, said veil including said matrix material. 
     
     
       3. A tubular composite member according to claim I having the further improvement comprising at least one outer ply having at least a biaxial fiber component disposed with said matrix material and located between said intermediate ply and said exterior ply.   
     
     
       4. A tubular composite member according to claim 1 wherein said fiber component of said intermediate ply includes a first axial fiber and second and third fibers each oriented diagonally relative to said first fiber, so that said first, second, and third fibers together form a triaxial fiber component.   
     
     
       5. A tubular member according to claim 1 further comprising an internal web-like reinforcement spanning across the tubular interior of the member between and secured to two spaced apart wall portions. 
     
     
       6. A tubular member according to claim 5 wherein said web-like reinforcement includes a fiber component disposed with said matrix material. 
     
     
       7. A tubular member according to claim 5 wherein said web-like reinforcement includes a substantially rigid core disposed between fibers disposed with said matrix material. 
     
     
       8. A tubular member according to claim 1 wherein said member has a cross section transverse to said longitudinal axis in the form of a closed plane figure having at least four sides, and with at least two opposed wall portions. 
     
     
       9. A tubular member according to claim 8 having the further improvement wherein said two opposed wall portions have a first medial thickness and have a greater thickness than said first thickness at longitudinally-extending edges thereof. 
     
     
       10. A tubular member according to claim 8 having the further improvement wherein said member has a lesser wall thickness at the middle of said two opposed wall portions then at axially-extending edges of said opposed wall portions. 
     
     
       11. A tubular member according to claim 8 wherein said two opposed wall portions are symmetrically concave. 
     
     
       12. A composite member according to claim 1 wherein the fiber materials of said biaxial fiber component and of said axial fiber component are selected from the group of fiber materials consisting of polyester, glass, carbon, aramid, and mixtures thereof. 
     
     
       13. An axially extending tubular composite member having a plurality of plies and having primary bending stiffness along a longitudinal axis, said member having the improvement comprising A. at least one interior ply having at least a biaxial fiber component with a matrix material,   B. at least one intermediate ply having at least an axial fiber component disposed with said matrix material, said intermediate ply being exterior to said interior ply,   C. at least one outer ply having at least any one of (i) a biaxial fiber component and (ii) an axial fiber component, said fiber component being disposed with said matrix material and said outer ply being exterior to said intermediate ply, and   D. an internal web-like reinforcement spanning across the tubular interior of the member between and secured to two spaced apart wall portions.   
     
     
       14. A tubular composite member according to claim 13 having the further improvement comprising a further ply exterior to said outer ply and having a woven fiber component. 
     
     
       15. A tubular composite member according to claim 13 having the further improvement comprising a surface veil coating at least one of the inner surfaces of said interior ply and the outer surfaces of said exterior ply. 
     
     
       16. An axially extending composite tubular member having a plurality of plies and having primary bending stiffness along a longitudinal axis, and comprising at least one interior ply having a matrix material and a first fiber component with fibers oriented at an angle relative to said longitudinal axis of between thirty degrees and sixty degrees, and more particularly between forty degrees and fifty degrees, and   an internal weblike reinforcement spanning across the tubular interior of the member between and secured to two spaced apart wall portions,   said first fiber component being structured to provide significant torsional stiffness to the composite member and said internal weblike reinforcement being structured to provide significant impact resistance to the composite member.   
     
     
       17. An axially extending tubular composite member having a plurality of plies and having primary bending stiffness along a longitudinal axis, said member having the improvement comprising A. at least one interior ply having at least a biaxial fiber component with a matrix material,   B. at least one intermediate ply having at least one axially extending fiber component disposed within said matrix material, said intermediate ply being exterior to said interior ply, and   C. at least one exterior ply having at least a biaxial fiber component disposed with said matrix material, said exterior ply being located exterior to said intermediate ply.